HR: 0800h
AN: AE31A-0052    [Abstracts]
TI: Observations of X-Rays and Electric Field in Thunderstorms: Revisited
AU: * Eack, K B
EM: keack@nmt.edu
AF: Langmuir Laboratory New Mexico Tech, 801 Leroy Place, Socorro, NM 87801, United States
AU: Beasley, W H
EM: whb@ou.edu
AF: School of Metorology University of Oklahoma, 120 David L. Boren Blvd., Norman, OK 73072, United States
AU: Rust, D
EM: Dave.Rust@noaa.gov
AF: National Severe Storms Laboratory, 120 David L. Boren Blvd., Norman, OK 73072, United States
AB: In 1994 and 1995 we launched balloon-borne x-ray spectrometers and electric-field meters into thunderstorms to test the hypothesis that strong electric-fields could accelerate cosmic-ray secondary electrons and produce bremsstrahlung x-rays. There were four flights into the stratiform regions of mesoscale convective systems. In three of the flights, increases in x-ray intensity were observed in conjunction with strong electric fields, while on flight four, large x-ray pulses were observed above the MCS. Both negative and positive polarity electric fields (as referenced to the vertical field) produced x rays. Each of these events lasted for times on the order of ten of seconds, demonstrating that it was the strong quasi-electrostatic field, not lightning, that caused the x-ray emissions. It was also observed that the increased x-ray intensity would return to near background levels after lightning reduced the local electric field. The observations indicate that x-rays observed above background are produced by strong electric field present in thunderstorms, most likely through a runaway electron process. In addition, they also show that the runaway electron process can occur over long periods of time without initiating a large-scale lightning discharge.
DE: 3304 Atmospheric electricity
DE: 3324 Lightning
DE: 3360 Remote sensing
SC: Atmospheric and Space Electricity [AE]
MN: 2007 Fall Meeting